郑州近54年降水变化的多时间尺度分析   总被引：5，自引：0，他引：5  

刘忠阳  王勇  丁园圆  杨海鹰  杜子璇 《气象科技》2005,(Z1)

利用Morlet小波分析方法,对1951~2004年郑州市年降水距平时间序列的小波变化特征进行分析,揭示降水变化的多时间尺度结构,分析其中存在的主要周期振荡和突变点,并与功率谱分析结果进行比较。结果表明:郑州市年降水存在多时间尺度的周期变化特征,郑州市年平均降水存在3 a、准5 a、准9 a和准21 a的主周期。郑州市降水变化存在着明显的多时间尺度,即年代际尺度和年际尺度的周期性变化。郑州市降水变化还显示出自己的突变点分布及其位相结构。在降水量总趋势下降的前提下,2004年后的一段时间还将处在一个偏多期。  相似文献   

阿尔金断裂不同时间尺度下的滑移速率及构造意义   总被引：2，自引：0，他引：2  

熊熊  王继业  滕吉文 《地质科技情报》2006,25(3):21-28

阿尔金断裂是亚洲大陆最大、也是最活跃的走滑断层之一.一般认为,印度板块与欧亚大陆间的汇聚通过地壳增厚与沿阿尔金等主要深大断裂的侧向滑移2种机制被青藏高原造山带的地壳形变所吸收.由于这2种机制所预测的阿尔金断裂的左旋滑移速率相差甚巨,因此,阿尔金断裂的滑移速率成为判断2种机制相对重要性的重要依据.采用地质学、大地测量学及数值模拟方法对阿尔金断裂滑移的研究结果表明,阿尔金断裂的滑移速率呈长期减小的趋势;青藏高原经历了由块体的侧向挤出向地壳增厚的转变过程;阿尔金断裂在不同地质时间尺度下的滑移速率尚需精确确定;单纯将阿尔金断裂滑移速率的大小作为判断青藏高原构造模式的依据也是应该受到质疑的.  相似文献   

基于截断1-范数损失函数的鲁棒超限学习机     

王快妮  曹进德 《南京气象学院学报》2019,11(4):453-459

对噪声和异常值较敏感、鲁棒性差是超限学习机（ELM）的主要问题.在1-范数损失函数的基础上,提出截断1-范数损失函数来抑制噪声和异常值的影响,建立了基于截断1-范数损失函数的鲁棒ELM模型.通过迭代重赋权算法求解对应的优化问题,并利用4个模拟数据集和9个真实数据集验证模型的有效性.数值实验结果表明,在噪声环境下鲁棒ELM的泛化性能优于对比方法,并且具有较强的鲁棒性,尤其是在异常值比例较大的情形下.  相似文献   

Mechanisms of Atlantic Meridional Overturning Circulation (AMOC) Variability in a Coupled Ocean–Atmosphere GCM简   总被引：1，自引：0，他引：1  

Boyin HUANG  ZHU Jiang  YANG Haijun 《大气科学进展》2014,31(2):241-251

The mechanisms involved in the variability of Atlantic Meridional Overturning Circulation （AMOC） are studied using a 2000-yr control simulation of the coupled Fast Ocean-Atmosphere Model （FOAM）.This study identifies a coupled mode between SST and surface heat flux in the North Atlantic at the decadal timescale,as well as a forcing mode of surface heat flux at the interannual timescale.The coupled mode is regulated by AMOC through meridional heat transport.The increase in surface heating in the North Atlantic weakens the AMOC approximately 10 yr later,and the weakened AMOC in turn decreases SST and sea surface salinity.The decreased SST results in an increase in surface heating in the North Atlantic,thus forming a positive feedback loop.Meanwhile,the weakened AMOC weakens northward heat transport and therefore lowers subsurface temperature approximately 19 yr later,which prevents the AMOC from weakening.In the forcing mode,the surface heat flux leads AMOC by approximately 4 yr.  相似文献   

岩浆成矿系统的尺度效应   总被引：2，自引：0，他引：2  

罗照华  苏尚国  刘翠 《地球科学与环境学报》2014,(1):1-9

小岩体成大矿理论强调了岩浆侵入体的几何尺度与内生金属成矿作用的有机联系,但这种联系的实质尚理解甚少。简要分析了岩浆成矿系统的基本问题,聚焦于侵入体几何尺度与几种关键控矿因素的内在联系。利用前人提出的固相线前锋迁移距离与冷却时间之间的函数关系估算了岩浆侵入体固结的时间尺度,发现小岩体的存活时间尺度与超大型矿床的形成时间尺度一致。基于斯托克定律的估算,含有暗色微粒包体的小岩体以岩浆快速上升为特征,符合流体中成矿金属溶解度与压力(P)、温度(T)正相关的实验结果。分析了岩浆产量与源区减压速率和所产生岩浆中挥发分含量之间的关系,提出大规模岩浆活动之后岩浆产量必然逐渐减少,因而流体-熔体比值逐渐增加。据此认为,超大型矿床可形成于紧接着大规模岩浆活动之后,并以长英质岩浆成矿系统为例将其称为岩基后成矿作用。因此,岩浆成矿系统的尺度效应是一种重要的地质效应,尺度效应分析支持小岩体成大矿理论。  相似文献   

Self-Similar Characteristic for the Ramp Structures of Wind Speed          下载免费PDF全文

SONG Zong-Peng  HU Fei  XU Jing-Jing  CHENG Xue-Ling 《大气和海洋科学快报》2014,(4):320-323

Time series of wind speed are composed of large and small ramp structures. Data analysis reveals a power law relation between the linear slope of ramp structures and the time scale. This suggests that these ramp structures of wind speed have a self-similar characteristic. The lower limit of the self-similar scale range was 2 s. The upper limit is unexpectedly large at 27 rain. Data are collected from grassland, city, and lake areas. Although these data have different underlying surfaces, all of them clearly show a power law relation, with slight differences in their power exponents.  相似文献   

Variations of the temperature and solar activity in China     

MingQi Li  QuanSheng Ge  ZhiXin Hao  JingYun Zheng 《寒旱区科学》2014,6(6):0531-0539

In this paper we analyze daily mean, minimum, and maximum temperature data collected at 119 meteorological stations over five regions of China during the period 1951-2010. The series of minimum, maximum, and mean temperatures from each climatic region have similar signatures, but there are differences among the five regions and the countrywide average. The results indicate that the periods of faster warming were not synchronous across the regions studied： warming in northeast China and Tibet began in 1986, while in central-east, southeast, and northwest China the warming emerged in 1995. Furthermore, central-east and northwest China, and Tibet, have warmed continuously since 2000, but the temperature has decreased during this period in southeast China. We evaluated the evolution of these temperature series using a novel nonlinear filtering technique based on the concept of the lifetime of temperature curves. The decadal to secular evolution of solar activity and temperature variation had similar signatures in the northeast, southeast, and northwest re- gions and the average across the whole country, indicating that solar activity is a significant control on climate change over secular time scales in these regions. In comparison with these regions, the signatures were different in central-east China and Tibet because of regional differences （e.g., landforms and elevation） and indirect effects （e.g., cloud cover influencing the radiation balance, thereby inducing climate change）. Furthermore, the results of wavelet analysis indicated that the El Nino Southem Oscillation （ENSO） has had a significant impact on climate change, but at different times among the regions, and these changes were most probably induced by differing responses of the atmospheric system to solar forcing.  相似文献   

Multiple temporal scale relationships of bankfull discharge with streamflow and sediment transport in the Yellow River in China     

Yan-yan ZHANG  De-yu ZHONG  Bao-sheng WU 《国际泥沙研究》2013,28(4):496-510

This paper presents a study on the characteristics of multiple time scales of bankfull discharge and its delayed response to changes of flow conditions using continuous wavelet analysis for data from selected hydrological stations in the Yellow River basin. Results showed that bankfull discharge series had one or two dominant time scales. For example, the Huayuankou station in the lower reach of the Yellow River had two dominant time scales of 19-20 years and 545 years. The dominant time scales of the bankfull discharge series were generally consistent with the dominant time scales of water discharge and sediment concentration series, indicating that the channel morphology inherits the characteristics of the hydrological system in terms of multiple time scales. In addition, the wavelet coefficients of the bankfull discharge series had a phase difference in relation to those of the sediment concentration series, with a delay time that varied from 3 to 16 years at different sites. This delay time or relaxation time is a result of the delayed response of bankfull discharge to flow conditions, which was significant for channel adjustments in response to changes of flow conditions. The findings of the multiple time scales and the delayed response are of importance for further study of channel morphology of fluvial systems.  相似文献   

基于小波变换的北京地区1724～2009年降水量多尺度分析   总被引：2，自引：1，他引：1  

郭高轩  辛宝东  朱琳  沈媛媛  陆海燕  许亮  纪轶群 《水文》2012,32(3):29-33

基于小波分析方法,对1724~2009年北京气象站年降水量序列的变化特征进行了分析。结果表明,北京地区年降水量在其计算时域内各时间尺度分布不均匀,具有明显的局部化特征;其中,19~23a的时间尺度,震荡中心分别在1889年和1979年;35~37a左右的时间尺度主要发生在1920~1928年、1950~1960年和1983~1991年;83~87a的时间尺度在整个计算时域上均有发生,1769~1859年间表现明显。分析结果显示北京地区年降水量具有21a、35a和86a左右的主周期,其中86a左右的周期振荡最强,为第一主周期。计算的趋势表明,未来10余年北京仍属于降水偏少的时期。  相似文献   

全球海表温度在不同时间尺度的主模态对比分析     

刘鹏  江志红  于华英  秦怡 《地球科学进展》2014,(7)

利用1880—2009年HadISST资料,去掉百年全球变暖的信号,研究发现东太平洋、北太平洋和北大西洋都有较强的年际和年代际振荡信号,特别是赤道东太平洋南侧的年代际振荡是不容忽视的。对全球范围的海表温度资料做EOF分析发现,存在3种主要的全球尺度信号,第一模态为太平洋型、第二模态为北大西洋型以及第三模态为赤道中太平洋型。特别指出,第三模态是CP ENSO在全球模态中的表现。这3种模态在年际和年代际尺度都有显著的信号,在无滤波的情况下,3种模态方差贡献之和为34%。在年代际以上时间尺度范围,3种模态方差贡献之和为61%。在各种时间尺度中,这3种信号与全球平均温度都有一定的联系,尤其第一、二模态的影响最为重要,在年代际尺度中,第一、二模态方差贡献之和达到50%。2005年以后全球并没有明显增温,可能与前2个模态同时下降有关。  相似文献